Lecture 3, Part B: Ethers in Organic Chemistry

Overview

• Focus on ethers, following the study of alcohols.
• Covers naming, classification, properties, and diethyl ether exploration.

Definition of Ethers

• Ether: Compound with an oxygen atom bound to two alkyl or aryl groups.
  • Alkyl groups: Non-aromatic carbon groups.
  • Aryl groups: Aromatic (ring) structures.
• Types:
  • Symmetrical Ethers: Same R groups.
  • Asymmetrical Ethers: Different R groups.

Naming Ethers

• IUPAC System:
  • Name as substituted alkane: Alkoxy-alkane.
  • "Alkoxy" shows position of OR group on carbon chain.
• Common Names:
  • Alkyl groups in alphabetical order + "ether".
  • Symmetrical example: "Diethyl ether".
  • Asymmetrical example: "Methyl propyl ether".
• Historical Names:
  • Anisole for methylphenyl ether.

Properties of Ethers

• Inertness
  • Used as solvents due to low reactivity.
• Boiling Points
  • Diethyl ether: Molecular mass 74, Boiling point 35°C.
  • Compare with pentane (36°C) and butan-1-ol (118°C).
  • Lower boiling point than alcohols due to lack of hydrogen bonding.

Hydrogen Bonding in Alcohols

• Oxygen: Electronegative; creates dipole with hydrogen.
• Hydrogen Bonding: Causes higher boiling points in alcohols.
  • Example: Ethanol molecules self-assemble through hydrogen bonds.

Uses of Ethers

• Solvent Properties
  • High solubility with low boiling point.
  • Non-reactive, preventing side reactions.
  • Does not mix with water; useful for organic extractions.
• Flammability and Risks
  • Highly flammable.
  • Can form explosive peroxides.

Historical Use as Anesthetic

• First used as anesthetic in 1846.
  • Demonstrated by Dr. Morton using an inhaler.
  • Effective for over 100 years.
• Precautions needed due to flammability.

Summary

• Ethers: Named through IUPAC and common systems.
• Low boiling points; inert nature makes them useful in laboratories.
• Risks include flammability and peroxide formation.

Additional Resources

• Video on curly arrows and different arrows in organic chemistry.